Percutaneous Endoscopic Lumbar Diskectomy: Transforaminal Approach

2 Percutaneous Endoscopic Lumbar Diskectomy: Transforaminal Approach

Akarawit Asawasaksakul, Ketan Deshpande, Gun Choi, and Alfonso García

2.1 Introduction

Kambin and Sampson in 1986 1 and Hijikata² in 1989 performed nonvisualizing nucleotomy via a posterolateral approach. Since then, due to advancements in technology and development of the visualizing endoscopic system, along with the irrigation channel and working portal, as well as specific endoscopic instruments, endoscopic spine surgery has become popular and yields better outcomes than ever before.^3,4,5,6,7,8

In addition to the interlaminar approach described by Choi et al in 2006,⁹ the transforaminal posterolateral approach is an endoscopic approach that can be used for several types of disk pathology.^6,10,11,12 This chapter describes the surgical technique and outlines crucial points in the procedure (Video 2.1 and Video 2.2).

2.2 Step 1: Position and Anesthesia

• Percutaneous endoscopic lumbar diskectomy (PELD) by the transforaminal approach is performed under conscious sedation with the patient in the prone position on a radiolucent operating table.

• The patient’s hips and knees should be in flexion to avoid stretching the lumbosacral plexus (Fig. 2.1).

• Lumbar lordosis should be obliterated using a Wilson’s frame or sponge bolsters; this helps to increase the anteroposterior dimensions of the foramen, which facilitates the passage of the working cannula (Fig. 2.2).

• Level marking is done before scrubbing/draping to facilitate changes in position if needed (Fig. 2.3).

• Conscious sedation provides adequate analgesia and simultaneously allows continuous feedback from the patient, which helps avoid damage to neural structures.

• Midazolam (0.05 mg/kg IM) is administered half an hour before surgery, followed by 50 μg of fentanyl or remifentanil intraoperatively as necessary for pain.

2.3 Step 2: Skin Entry Point

• Axial MRI or CT is used to get an approximate idea of the distance of the skin entry point from the midline (Fig. 2.4). The needle trajectory is planned to target the ruptured fragment while avoiding the contents of the peritoneal sac.

Fig. 2.1 Patient positioning.

Fig. 2.2 Diagram illustrating the increase in foraminal dimensions with obliteration of lumbar lordosis.

Fig. 2.3 Level marking.

Fig. 2.4 Needle entry point estimation on preoperative MRI.

Fig. 2.5 Skin infiltration with local anesthetic.

Fig. 2.6 Intramuscular infiltration with local anesthetic.

Fig. 2.7 (a,b) Needle tip location on AP and LAT views.

2.4 Step 3: Needle Insertion

• The skin is infiltrated with 1% lidocaine (~ 2–3 mL), and the intramuscular plane is infiltrated with 3 to 4 mL of 1% lidocaine using a 23 G spinal needle (Fig. 2.5, Fig. 2.6)

• The inclination of the needle trajectory is highly subjective and varies from patient to patient, depending on the location of the pathology, but usually the needle is directed from cranial to caudal, toward the inferior end plate at an angle of 10 to 15 degrees.

• The first bony resistance encountered is the superior facet; at this stage, one should confirm the needle location on both anteroposterior (AP) and lateral (LAT) views on C-arm fluoroscopy.

• The beveled end of the needle can be used to pass ventral to the facet. When the bevel of the needle is facing dorsally, the needle will tend to move ventrally; this helps the needle tip to skive offthe undersurface of the facet.

• The location of the needle tip is again confirmed in both AP and LAT planes (Fig. 2.7).

• Epidural anesthesia: liberal use of lidocaine 1% solution (~ 5–6 mL) around the epidural region is recommended before puncturing the annulus; this step helps reduce the pain generated during the entry of the dilator into the annulus.